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Chapter 12 cell cycle
Holt biology The cell cycle
Chapter 12 the cell cycle
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Regulation of Cell Cycle and Cancer
1. Introduction
All organisms are made of cells that grow by cell division. An adult human being consists of about 100000 billion cells. Dying cells are replaced by a large number of unceasingly dividing cells. A cell duplicates its chromosomes, segregates the chromosomes, and divides into two. These ordered sequences of events are called a cell cycle. 2001 Nobel Prize in Physiology or Medicine to Hartwell, Hunt, Nurse and 1998 Lasker Prizes in Basic Medical Research to Hartwell, Masui, Nurse have made important discoveries about the regulation of a cell cycle. Understanding the regulation of a cell cycle is seminal to understanding why and how cancer cells are formed. In this review, I focus on how these crucial discoveries made progress in understanding cell cycle regulation and leading to understanding cancer cell and cancer therapy.
2. Overview of Cell Cycle
Eukaryotic cells have their chromosomes contained in a nucleus. Unicellular orgasisms such as amoebas and yeast, or multi-cellular organisms such as plants and animals consist of eukaryotic cells. Human being consist of approximately 1 billion cells per gram tissue. DNA located in 23 pairs of chromosomes is contained in each cell nucleus. Schleiden in 1838 and Schwann in 1839 made very important discoveries that we consist of cells, and Remark discovered that cells prolifarate through division in 1850. Three decades ago, the molecular mechanisms that regulate the cell cycle and thus cell division was able to be identified. It has been known that these vital mechanisms are conserved through evolution and function in the same way in eukaryotic organisms.
The cell cycle generaly consists of four phases. Fir...
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... over normal proliferating cells (Figure 1) It is important to target events taking place at the same time in the cell cycle in order to boost effectiveness of the arrest and the results. In addition, it is important to characterize tumors precisely in order to clarify where the deficiencies on the cell cycle control are accrued and which of the phases have to be targeted for successful therapy. Furthermore, in the future, identification of new tumor specific isoenzymes will be necessary to characterize the cell cycle accurately and comprehend the differences between normal cells and cancer cells for the design of novel anticancer therapies (Diaz-Moralli, et al. 2013).
Table 1. Cancer therapy researches and targets. (Source: Diaz-Moralli, et al. 2013)
Bolded CDKs are most specific targets when the drugs affect more than one.
Table 1 (continued)
There are many different cells that do many different things. But all of these cells fall into two categories: prokaryotic and eukaryotic cells. Eukaryotic cells contain a nucleus and are larger in size than prokaryotic cells. Prokaryotic cells do not contain a nucleus, are smaller and simpler than eukaryotic cells. Two of their similarities are they both have DNA as their genetic material and are covered by a cell membrane. Two main differences between these two cells are age and structure. It is believed that prokaryotic cells were the first forms on earth. They are considered primitive and originated approximately 3.5 billion years ago. Eukaryotic cells have only been around for about a billion years. There is strong evidence that suggests eukaryotic cells may be evolved from groups of prokaryotic cells that became interdependent on each other (Phenotypic analysis. (n.d.).
The Lives of a Cell: Notes of a Biology Watcher by Lewis Thomas consists of short, insightful essays that offer the reader a different perspective on the world and on ourselves.
Strategy to target cancer stem cells: The identification of CSC is essential for development of better and effective therapeutic strategies. The drugs used in the current therapies and treatments target not only the tumor cells, but also, the norm...
Do you know how you are able to run long distances or lift heavy things? One of the reasons is cellular respiration. Cellular respiration is how your body breaks down the food you’ve eaten into adenosine triphosphate also known as ATP. ATP is the bodies energy its in every cell in the human body. We don’t always need cellular respiration so it is sometimes anaerobic. For example, when we are sleeping or just watching television. When you are doing activities that are intense like lifting weights or running, your cellular respiration becomes aerobic which means you are also using more ATP. Cellular respiration is important in modern science because if we did not know about it, we wouldn’t know how we are able to make ATP when we are doing simple task like that are aerobic or anaerobic.
Stem cells help us to maintain and heal our bodies, as they are undifferentiated cells, their roles are not yet determined. They have the ability to become anything during early life and growth. Stem cells come from two sources, namely: embryonic stem cells (embryo’s formed during the blastocyst phase of embryological development) and adult stem cells (see figure 3).
Cancer starts when certain cells in the body are mutated or changed and begin to divide. Cancerous cells grow differently than normal cells, instead of progressing through the normal cell lifecycle, cancer cells continue to grow and create more abnormal cells. A specific trait of cancer cells is that they have the ability to infiltrate and grow into surrounding tissues, developing out of control and causing serious damage to the host (Vincent, 2008). Cells become cance...
This paper focuses on the benefits of stem cell research in the medical and nursing field. New technology is always being created to help us understand the way the human body works, as well as ways to help us improve diseased states in the body. Our bodies have the ability to proliferate or regrow cells when damage is done to the cells. Take for example the skin, when an abrasion or puncture to the skin causes loss of our skin cells, the body has its own way of causing those cells to regrow. The liver, bone marrow, heart, brain, and muscle all have cells that are capable of differentiating into cells of that same type. These are called stem cells, and are a new medical tool that is helping regrow vital organs in our body to help us survive. Stem cells can come from adult cells, or the blastocyst of the embryo. The cells that come from these are undifferentiated, and can be specialized into certain cell types, making them available for many damaged tissues in the body. While using stem cells in the body is a main use, they are also being used to help doctors understand how disease processes start. By culturing these cells in the lab and watching them develop into muscles, nerve cells, or other tissues, researchers are able to see how diseases affect these cells and possibly discover ways to correct these diseases. While researchers have come very far in using stem cells, there are still many controversies to overcome when using these cells.
The cell cycle is the process by which cells progress and divide. In normal cells, the cell cycle is controlled by a complex series of signaling pathways by which a cell grows, replicates it’s DNA and divides, these are called proto-oncogenes. A proto-oncogene is a normal gene that could become an oncogene due to mutations. This process has mechanisms to ensure that errors are corrected, if they are not, the cells commit suicide (apoptosis). This process is tightly regulated by the genes within a cell’s nucleus. In cancer, as a result of genetic mutations, this process malfunctions, resulting in uncontrolled cell proliferation. Mutations in proto-oncogene or in a tumour suppressor gene allow a cancerous cell to grow and divide without the normal control imposed by the cell cycle. A change in the DNA sequence of the proto-oncogene gives rise to an oncogene, which
Healthy cells grow and divide in a way to keep your body functioning properly. But when a cell is damaged and becomes cancerous, cells continue to divide, even when new cells aren't...
The nucleus is one of the most important organelles in a eukaryotic cell. The shape of the nucleus is generally spherical, it should be oval, disc formed reckoning on the sort of cell. The nucleus was found by Robert Brown in 1831 while he was looking at orchids under a microscope. He discovered a blurred area in the cells of the flowers and called it the areola or the nucleus.
In conclusion, the nucleus is an endosymbiont of bacteria and archaea. The host cell most likely did not come from the bacteria. The host cell, chronocyte, was not a prokaryotic cell but one that had a cytoskeleton composed of actin and tubulin and a complex membrane system. The chronocyte contributed to the end product that is the euaryotic cell. Its contributions were the cytoskeleton, endoplasmic reticulum, Golgi apparatus, and major intracellular control systems. (3)
Cells are able to grow and reproduce. Cells reproduce by splitting and passing on their genes (hereditary information) to Daughter cells. The nucleus always divides before the rest of the cell divides. Therefore each daughter cell contains their own nucleus. The nucleus controls the cells activities through the genetic material DNA. The cells in a body are all the same except the gametes they were all made from one cell, the Zygote. This is the cell that was formed when two gametes from your parents fused.
From my reading I learned that cellular respiration is a multi-step metabolic reaction type process that takes place in each living organism 's cell rather it be plant or animal. It’s my understanding that there are two types of cellular respiration, one called aerobic cellular respiration which required oxygen and anaerobic cellular respiration that does not require oxygen. In the anaerobic cellular respiration process, unlike the aerobic process oxygen is not required nor is it the last electron acceptor there by producing fewer ATP molecules and releasing byproducts of alcohol or lactic acid. The anaerobic cellular respiration process starts out exactly the same as anaerobic respiration, but stops part way through due to oxygen not being
The membrane surrounding the nucleus in eukaryotic cells, separate the nucleus from the cytoplasm. Most of the cells we used in the experiments held, were multicellular or consisting of more than one cell. A variety of cells were used in completing the experiments. We used union cells, cheek cells, potato cells, and Elodeo cells. We also used Planaria which is a unicellular organism.
Prokaryotic cells do not have a nucleus. The chromosomes which are found in prokaryotes are usually spread in the cytoplasm. In eukaryotic cells the chromosomes remain together inside the nucleus and there is a clear nuclear membrane that is surrounding the nucleus.